A medical testing company called Quest Diagnostics analyzed decades worth of drug tests – about 125 million of them – and found that only 3.6-percent came back positive for cocaine and marijuana.

That’s down from more 13-percent in 1988.

Seems like a good trend. But there were some exceptions beginning with prescription drugs. Positive tests for Vicodin and Oxycontin were up sharply over the past few years.

And researchers warn the lower rates of pot and cocaine use could also be due to the fact that more people are beating the tests. Manipulating them. I won’t get into how that’s done but selling tools to fool these tests has become an industry of its own.

And those are just a couple of reasons why drug testing is becoming more complicated in the work place. Especially in states like Massachusetts that have legalized medical marijuana.

Almost two dozen states have done so.

And many companies in those states may have to re-write their policies on drug testing or risk legal action. Indeed, The Wall Street Journal reports that companies are being sued more often for punishing or firing people for smoking pot after hours.